This invention relates to low oil content food products, such as corn chips and potato chips. More particularly, this invention relates to a process for removing oil from fried chip products by extraction with liquid carbon dioxide. Still more particularly, this invention relates to a process for removing more than 50%, preferably about 75%, of the oil from fried chips by extraction with liquid carbon dioxide. Even more particularly, this invention relates to a process of making fried chip products including deep frying chips in oil, extracting oil from the fried chips to produced reduced oil content fried chips, and recovering the extracted oil for further use, such as reuse in the frying process. This invention also relates to low oil content fried chips produced by the foregoing methods.
Chip food products such as potato chips and corn chips are typically produced by deep frying in oil. While such preparation yields chips which are highly desirable in terms of flavor and texture, it also yields chips with an oil content of about 30% to about 40% by weight. Such a large oil content is frequently viewed as unhealthy, and there has arisen a demand for chips having a reduced oil content. Attempts to produce such chips have encountered difficulty in achieving both a substantial reduction in oil content and acceptable flavor and texture. Accordingly, low oil chips presently marketed have only about 25%-33% reduction in oil content.
Until the present invention, two techniques have been employed to produce potato chips with a low oil content. The first technique employs the use of an alternative cooking process to conventional deep fat frying. As an example, partially cooked and processed potatoes can be mashed, extruded or otherwise formed into chip shaped articles, lightly sprayed with a vegetable or animal based oil, and then roasted in hot air to complete the cooking process. These products have a reduced oil content compared to potato chips deep fried in oils. However, these products do not have the appearance, texture or flavor of fried potato chips.
The second technique for producing a low-oil potato or corn chip is to deep fry sliced potatoes or corn chips in vegetable or animal base oils and subsequently remove some fraction of the oil from the fried chip. At least two process schemes are known for removing the oil from the fried chip. In the first scheme, a combination of heat, and/or sweeping with an inert gas or liquid, and/or a partial vacuum is used to remove some fraction of the oil from the fried chip. This process reportedly is limited to oil reductions of 33% by weight. Further reductions result in chips with unacceptable texture and flavor characteristics.
The second process scheme to remove oil from fried chips involves the use of supercritical carbon dioxide to remove some fraction of the oil from the fried chip. For instance, as disclosed in Hannigan, "Extraction Process Creates Low-Fat Potato Chips", Food Engineering, July, 1981, fried potato chips are placed in a "short and fat" processing vessel through which is passed a stream of supercritical carbon dioxide. Fats and oils dissolve into the carbon dioxide which is then routed to a separator for cleaning and recycling. According to the Hannigan article, only up to 50% of the fat can be removed while still producing potato chips with texture and flavor characteristics that are similar to the original product.
It is believed that supercritical carbon dioxide extraction of oil from fried potato chips, as proposed in the Hannigan article, has never been commercially practiced. It is believed that the reason for this is that the supercritical carbon dioxide oil extraction process has been found to be uneconomical on a commercial scale.
It is therefore a general object of the invention to provide a method of producing low oil content food chip products.
It is a further object of the invention to provide low oil content food chip products having flavor and textures comparable to convention deep fried chip products.
It is a further object of the invention to provide a method for making low oil content food chip products which may be used with conventional deep frying techniques.
It is a further object of the invention to provide a method for making low oil content food chip products having an oil content of less than 50%, desirably on the order of 25%, of the oil content of conventional deep fried chip products.
It is a further object of the invention to provide a method of making low oil content food chip products which may be economically utilized on a commercial scale.